1. Field of the Invention
This invention relates to land vehicles, such as a passenger car or truck that has a side-looking pre-crash sensor for anticipating impact by a closing object, such as another motor vehicle, from a direction that is non-parallel to the direction of travel of the host vehicle. Such a sensor is used in conjunction with an on-board occupant restraint system that is deployed to aid in restraint of an occupant upon detection of an impact of the closing object with the host vehicle exceeding a settable impact threshold. Such a sensor may employ any of several different technologies, such as radar, lidar, and optical recognition, for acquiring such closing objects.
2. Background Information
The state of the art is reflected by U.S. Pat. Nos. 5,694,130; 5,767,803; and 6,067,038 that were developed during a preliminary novelty search and disclose various on-board radar systems for detecting objects in the vicinity of a traveling host vehicle. For example, U.S. Pat. No. 5,767,803 discloses a forward-looking system that is said to be capable of distinguishing an on-coming vehicle that is in the same lane as the host vehicle from an on-coming vehicle that is not. The other two patents are concerned with ranging and scanning of a lead vehicle.
Although it is apparently not a subject of interest of discussion in those three patents, an on-board side-looking sensor can detect an object that is closing on the host vehicle from a direction that is lateral to the direction of travel of the host vehicle. Such a pre-crash sensor can anticipate impact of the closing object with the host vehicle and interact with an on-board occupant restraint system to set a threshold for a dynamic condition at which the restraint system will deploy an occupant restraint in the host vehicle. Insofar as the inventor is aware, such sensors have heretofore been aimed in a particular direction on a vehicle on the ostensibly tacit assumption that the antenna beam width will be sufficient to detect those closing objects that should be detected.
The invention arises through the inventor""s recognition that the foregoing assumption may not provide an optimal solution in all instances. The inventor has discovered that travel velocity of the host vehicle can at least under some conditions have a significant influence on certain aspects of detection capability. As a consequence of that discovery the inventor has created a system that takes that factor into account.
Whether a collision between a host vehicle and a closing object will occur depends on many factors including the range, the velocity, and the travel direction of the closing object and the velocity and the travel direction of the host vehicle, subject to any evasive action that may be taken. If a host vehicle has a side-looking pre-crash sensor aimed in a direction that is non-parallel to the longitudinal fore-aft axis of the vehicle, the limited azimuthal span of the sensor field of view may prevent successful detection of closing objects lying outside that span. Even if a closing object is successfully detected, the precision of data derived by processing information acquired by the sensor may be subject to tolerance because of various factors.
Accuracy of such information may be important in setting a deployment threshold for an on-board occupant restraint that is intended for deployment in consequence of detection of impacts from a direction that is non-parallel to a longitudinal fore-aft axis of the host vehicle.
In general, the solution provided by the present invention concerns aiming the sensor aperture, either electronically or mechanically, in correlation with the travel velocity of the host vehicle. Using a radar sensor for an example, the radar antenna beam remains aimed laterally, but in an increasingly forward direction as the forward travel velocity of the host increases.
Accordingly, one generic aspect of the present invention relates to an on-board system of a host vehicle traveling on land at a travel velocity in a direction of travel for acquiring a closing object having potential for impacting the host vehicle from a direction non-parallel to the direction of travel of the host vehicle. The system comprises an aperture having a field of view of limited azimuthal span and pointed in azimuth in a direction that is non-parallel to the direction of host vehicle travel for enabling acquisition of such an object, and apparatus for changing, in azimuth, the angle between the direction in which the aperture is pointed and the fore-aft axis of the host vehicle in correlation with travel velocity of the host vehicle in the direction of travel.
Another generic aspect of the present invention relates to a method for acquiring a closing object having potential for impacting a host vehicle from a direction non-parallel to the direction of travel of the host vehicle. The method comprises pointing an aperture that has a field of view of limited azimuthal span, in azimuth, in a direction that is non-parallel to the direction of host vehicle travel for enabling acquisition of such an object, and changing, in azimuth, the angle between the direction in which the aperture is pointed and the fore-aft axis of the host vehicle in correlation with travel velocity of the host vehicle in the direction of travel.
Still another generic aspect of the present invention relates to a host vehicle traveling on land at a travel velocity in a direction of travel comprising an on-board acquisition system for acquiring a closing object having potential for impacting the host vehicle from a direction non-parallel to the direction of travel of the host vehicle. The on-board system comprises a) an aperture having a field of view of limited azimuthal span and pointed, in azimuth, in a direction that is non-parallel to the direction of host vehicle travel for enabling acquisition of such an object, and b) apparatus for changing, in azimuth, the angle between the direction in which the aperture is pointed and the fore-aft axis of the host vehicle in correlation with at least one operating parameter related to operation of the host vehicle. An on-board processor processes data for one or more of the operating parameters related to operation of the host vehicle and data for one or more parameters related to closing of an acquired object derived at least in part from information acquired by the aperture to yield a processing result. Another on-board system is acted upon by the processing result.